Weld box auto roll sensing and positioning system

ABSTRACT

A system for monitoring and controlling a tube milling operation generally includes a weld box, a roll, a first sensor, and a controller. The roll is disposed within the weld box for simultaneously compressing and guiding a stock material. The first sensor detects either an actual load applied to the roll by the stock material or a position of the roll. The controller is in data communication with the first sensor and is operable to displace the roll along a first axis relative to the weld box in accordance with a difference between either the actual load and a load parameter or the roll position and a position parameter.

FIELD OF THE INVENTION

The present invention relates to a tube milling and welding system and, more particularly, to a feedback and control system for optimizing weld quality during the operation of a tube milling and welding system.

BACKGROUND OF THE INVENTION

Tube milling operations typically include taking stock material from a roll and through a series of operations converting it into a welded tube. The first step of the process includes removing burrs and uneven edges from the stock material. The stock material is then passed through a series of rolls mounted on shafts. The rolls apply a forging pressure to progressively curve the stock material toward the form of a cylinder. Once the material is formed substantially into a cylinder it is welded into a tube. In a typical milling operation, the rate of speed that the stock material travels through the mill and the position of each of the rolls are substantially fixed for a given size stock material. Therefore, any slight deformity in the stock material can decrease weld quality. Hence, timely inspection of each welded seam is critical. Without timely inspection, a tremendous amount of material can be wasted due to improper seam alignment and/or forging pressure.

Ideally, when cylindrical tubing is formed from stock material on conventional tube milling machines, a weld box joins opposing edges of the stock material at generally the same height. The most common method for inspecting the edge alignment is for an operator to hold a gloved hand on the welded seam. The operator then feels for inconsistencies in the welded seam. This method produces safety and accuracy concerns. Alternatively, an operator cuts samples of the welded tube and inspects sample seams under a microscope. Such inspection can be time consuming, cost prohibitive and due to the random nature of sample testing, ineffective. Yet another method of inspecting weld quality includes utilizing a digital camera to substantially continuously image the welded seam. The images are then presented on a monitor for a technician to inspect. However, as a result of the edge conditioning, tube forming, and welding processes, the welded seam and environment tend to be very dirty. Therefore, the image quality tends to be poor, resulting in an ineffective inspection.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of a tube mill arranged in accordance with the principles of the present invention;

FIG. 2 is a cross-sectional view taken through line II-II of FIG. 1;

FIG. 3 is a block diagram of a controller and a welding portion of the tube mill of FIG. 1; and

FIG. 4 is a flow chart illustrating a method of monitoring and controlling the tube mill of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

FIG. 1 depicts a tube mill 10 including a pre-stage portion 12, a welding portion 14, and a sizing and cutting portion 16. A roll of stock material 18 is introduced to the pre-stage portion 12. The stock material 18 includes a roll of sheet material such as sheet metal. The pre-stage portion 12 gradually forms the stock material 18 into a semi-tubular member 18 a of approximately 320 degrees. The semi-tubular member 18 a is then introduced to the welding portion 14 of the tube mill 10. The welding portion 14 simultaneously compresses the semi-tubular member 18 a into a substantially 360 degree cylinder and joins opposite edges thereof to provide a continuous tube 18 b of generally constant diameter. The tube 18 b then exits the welding portion 14 and is introduced to the sizing and cutting portion 16. The sizing and cutting portion 16 is adapted to cut the tube 18 b into a plurality of links (not shown) having predetermined lengths as may be desired. It should be appreciated that while the pre-stage portion 12 has been disclosed as producing a semi-tubular member 18 a of approximately 320 degrees, a pre-stage portion 12 producing a semi-tubular member having an alternative geometry is intended to be within the scope of the present invention.

It is envisioned that the pre-stage portion 12 includes a seam preparation station, a plurality of forming stations, an edge conditioning station, and a seam guide. The seam preparation station generally removes burrs from the edges of the stock material 18. This may be achieved with grinding wheels, wire brushes, or any other material removing means. The plurality of forming stations form the stock material 18 from a substantially planar member into the semi-circular member 18 a. This is achieved by forcing the stock material 18 through a series of rollers spaced progressively closer apart. The edge conditioning station de-burrs the edges of the stock material 18 a second time to ensure a controlled finish. The seam guide includes at least one fin for guiding the edges of the stock material 18 toward the welding portion 14 at a predetermined spacing that is suitable for welding.

FIG. 2 depicts the welding portion 14 including a weld box 20, a controller 22, and a weld apex 24. As described above, the stock material 18 travels through the welding portion 14 to be welded into a tube 18 b. More specifically, as the semi-circular member 18 a travels through the weld box 20 and beneath the weld apex 24, the weld apex 24 forms a substantially continuous weld bead joining the edges of the semi-circular member 18 a. In an exemplary embodiment, the weld box 20 is constructed of sheet metal and includes sidewalls 20 a having dual walled construction. The sidewalls 20 a are adapted to substantially continuously carry a coolant flow, such as chilled water. It is envisioned that the sidewalls 20 a may define an elongated serpentine channel between the dual walls for carrying the coolant flow. The coolant flow removes heat from inside the weld box 20 that is generated by forging and welding the stock material 18. It should be appreciated that while only the sidewalls 20 a have been disclosed as being dual walled, a weld box 20 having dual walled top and/or bottom walls is also intended to be within the scope of the present invention. It should further be appreciated that the weld box 20 is envisioned to include an inlet port (not shown) and an outlet port (not shown). The inlet port is for delivering the coolant flow to the sidewalls 20 a and the outlet port is for removing the coolant flow from the sidewalls 20 a, thereby providing a continuous flow. Furthermore, it is envisioned that the weld box 20 could be filled with an inert gas. In an exemplary embodiment, the weld box 20 is filled 98% with argon gas. The argon gas is heavier than oxygen, which comprises the remaining 2% of atmosphere in the weld box 20, and, therefore, serves to prevent impurities such as water, oil, or any other contaminant from obstructing the weld apex 24 during the welding and forming processes. Furthermore, an oxygen sensor (not shown) is employed to substantially continuously monitor the level of oxygen in the weld box 20 and terminate operation of the tube mill 10 if the level rises above 2%.

While the weld apex 24 forms the weld bead, the weld box 20 positions the stock material 18. The weld box 20 includes first and second rolls 26 rotatably supported on shafts 41. In an exemplary embodiment, the rolls 26 and shafts 41 are constructed of a thermally conductive material, such as aluminum or steel. The rolls 26 apply a forging pressure for compressing and guiding the stock material 18 through the weld box 20. The first and second rolls 26 include substantially parallel rotational axes, each identified by B, and a common lateral axis A. The lateral axis A is substantially perpendicular to the rotational axes B. The first and second rolls 26 each include concave forming surfaces 28 integrally formed with top caps 30 and bottom caps 32. In the embodiment illustrated, the forming surfaces 28 are designed to generally conform to the shape of the tube 18 b. The top and bottom caps 30, 32 include external cylindrical surfaces 30 a, 32 a. It should be appreciated, however, that rolls 26 having alternative geometries are intended to be within the scope of the present invention. For example, the rolls 26 may include cylindrical rolls. It should also be appreciated that in the embodiment illustrated, the shafts 41 rotatably supporting the rolls 26 are hollow. Similar to the sidewalls 20 a discussed above, the hollow shafts 41 are adapted to carry a coolant flow, such as chilled water. The coolant flow serves to remove heat from the rolls 26 generated by forging the stock material 18 during normal operation of the tube mill 10. It is envisioned that the hollow shafts 41 would also include an inlet port (not shown) and an outlet port (not shown) for delivering and removing the coolant flow therefrom.

For each of the first and second rolls 26, the weld box 20 further includes a vertical position sensor 34, a horizontal position sensor 36, a load sensor 38, and a roll translating device 40. The vertical and horizontal position sensors 34, 36 are in data communication with the controller 22. In an exemplary embodiment, the vertical and horizontal position sensors 34, 36 each include an optical transmitter and an optical sensor. For example, the optical transmitters may include laser-generating devices and the optical sensors may include charge coupled devices. The optical transmitters of the vertical position sensors 34 project an optical signal to a top surface of the rolls 26. The optical signals deflect off of the top surfaces of the rolls 26 and are received by the optical sensors. Similarly, the horizontal position sensors 36 project an optical signal to the external cylindrical surfaces 30 a of the top caps 30 of the rolls 26. The optical signals deflect off of the external cylindrical surfaces 30 a and are received by the optical sensors. The vertical and horizontal position sensors 34, 36 then send signals to the controller 22. The signals represent a characteristic of the optical signals received. For example, in one embodiment the position sensors 34, 36 send a signal identifying the magnitude of the optical signal received. The controller 22 then processes these signals to determine the vertical and horizontal positions of the rolls 26 relative to the weld box 20, as will be described in more detail below. It should be appreciated that while the vertical and horizontal position sensors 34, 36 have been disclosed herein as including optical-based position sensors, alternative positioning sensors such as sonar-based sensors or any other type of sensor operable to detect position is intended to be within the scope of the present invention.

The load sensors 38 each include a form of load cell. The load cells are each envisioned to include a linear strain gage load cell, a non-linear strain gage load cell, a piezoelectric load cell, or any other type of electromechanical load detecting device capable of serving the principles of the present invention. In the embodiment illustrated, the load cells each include a load button 39 operably connected to a strain-gage (not shown) disposed in the load sensor 38. The load sensors 38 also include a biasing member (not shown) such as a spring biasing the load buttons 39 toward the rolls 26. The load buttons 39 are in constant engagement with the external cylindrical surfaces 32 a of the bottom caps 32 of the rolls 26. Therefore, any displacement of the rolls 26 along axis A displaces the load buttons 39 and deforms the strain gages disposed in the load sensors 38. This deformation changes the electrical resistance across the strain gages. The load sensors 38 then send a signal representing this change in electrical resistance to the controller 22 for processing, which will be described in more detail below. It should be noted that during normal operating conditions, the stock material 18 being substantially uniform in size and construction, the stock material 18 should apply a substantially uniform force on the rolls 26. However, the stock material 18 may include discrepancies in size and construction that alter the force applied to the rolls 26. For example, a slightly wider or thicker portion of the stock material 18 may increase the force applied to the rolls 26. Alternatively, a slightly narrower or thinner portion of the stock material may decrease the force applied to the rolls 26.

Whenever a load discrepancy is identified, the controller 22 actuates the roll translating devices 40. The roll translating devices 40 are connected to shafts 41 rotatably supporting the rolls 26 about their rotational axes B. The roll translating devices 40 are operable to translate the rolls 26 along their rotational axes B, as well as along the lateral axis A. It is envisioned that each of the roll translating devices 40 may include a single multi-axis electrical motor, two single-axis electrical motors, a hydraulic actuator, or any other device or combination of devices actuable by the controller 22 and operable to serve the principles of the present invention.

FIG. 3 depicts the controller 22 including a processor 42, an electronic storage unit 44, and a user interface 46. The processor 42 of the controller 22 is in data communication with the roll translating devices 40, the vertical position sensors 34, the horizontal position sensors 36, and the load sensors 38. The electronic storage unit 44 is adapted to store a variety of operational parameters for the tube mill 10 and, more specifically, for the weld box 20. The operational parameters include horizontal roll position parameters, vertical roll position parameters, and load parameters. For example, the horizontal and vertical position parameters are envisioned to include a distance value identifying a distance that the rolls 26 are to be positioned from the position sensors 34, 36. The load parameters are envisioned to include a force value that the stock material 18 applies on the rolls 26 during normal milling operations. The user interface 46 includes a display device and an input device. In an exemplary embodiment, the display device includes a video monitor and the input device includes a keypad. The user interface 46 is adapted to display the operational parameters and any other relevant information to a technician. Furthermore, the user interface 46 is adapted to receive operational parameters to be stored in the electronic storage unit 44. In this manner, a technician may enter operational parameters for a plurality of different tube milling operations into the user interface 46. The user interface 46 then sends these parameters to the processor 42, which appropriately stores them in the electronic storage unit 44.

FIG. 4 depicts a flow chart illustrating a feedback and control process performed by the controller 22. Upon introduction of a specific size stock material 18 to the tube mill 10, the processor 42 receives information from a technician via the user interface 46. This information identifies the specific stock material 18 being formed. The processor 42 then retrieves a set of operational parameters from the electronic storage unit 44 matching that stock material 18, as identified by block 48. As stated above, the operational parameters include vertical position parameters, horizontal position parameters, and load parameters. Subsequently, the processor 42 receives a horizontal position signal from each of the horizontal position sensors 36 and a vertical position signal from each of the vertical position sensors 34, as identified by block 50. The processor 42 then compares the horizontal and vertical position signals to the horizontal and vertical position parameters retrieved from the electronic storage unit 44, as identified by block 52. If the processor 42 determines that the position signals match the position parameters, the processor proceeds to block 56 and receives load signals from the load sensors 38. Alternatively, if the processor 42 determines that any of the position signals do not match their respective position parameters, the processor 42 instructs the roll translating devices 40 to adjust the first and second rolls 26 in accordance with the difference between the position signals and position parameters, as identified by block 54. Once the rolls 26 are properly positioned, the processor 42 proceeds to block 56 and receives load signals from the load sensors 38.

During the forming and welding process, the processor 42 substantially continuously receives load signals from the load sensors 38, as identified by block 56. The processor 42, therefore, substantially continuously compares the load signals with the load parameters retrieved from the electronic storage unit 44, as identified at block 60. If the load signals match the load parameters, the processor 42 returns to block 50 and repeats the process. However, if the load signals do not match to the load parameters, the processor 42 sends a signal to each of the roll translating devices 40, as illustrated by block 62. The signals actuate the roll translating devices 40 to displace the rolls 26 along axis A. Then the processor 42 returns to block 56 to continue receiving and processing load signals until the load signals match the load parameters. Once the processor 42 determines that the load signals match the load parameters it returns to block 50 to repeat the entire control loop.

It should be appreciated that the above-described adjustments based on the load and position signals are performed substantially continuously throughout normal operation of the tube mill 10. This substantially continuous control loop ensures optimum edge alignment of the stock material 18 even when the stock material 18 includes a slight deviation in size or thickness. It should further be appreciated that in an exemplary embodiment, the load and position parameters may include ranges of distances and forces, respectively, representing satisfactory operating conditions. Thus, the processor 42 determines whether the position and load signals are within the ranges of parameters. Furthermore, it should be appreciated that while the weld box 20 has been disclosed as including two rolls 26, a weld box including more or less than two rolls 26 is intended to be within the scope of the present invention.

The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention. 

1. A system for monitoring and controlling a tube milling operation, comprising: a weld box; a roll disposed in said weld box for substantially simultaneously compressing and guiding a stock material; a first sensor for detecting one of an actual load applied to said roll by said stock material and a position of said roll along a first axis relative to said weld box; and a controller in data communication with said first sensor and operable to displace said roll along said first axis relative to said weld box in accordance with a difference between one of said actual load and a load parameter and said position of said roll and a first position parameter.
 2. A system for monitoring and controlling a tube milling operation, comprising: a weld box; a roll disposed in said weld box for substantially simultaneously compressing and guiding a stock material; a first sensor for detecting one of an actual load applied to said roll by said stock material and a position of said roll along a first axis relative to said weld box; a controller in data communication with said first sensor and operable to displace said roll along said first axis relative to said weld box in accordance with a difference between one of said actual load and a load parameter and said position of said roll and a first position parameter; and a second sensor in data communication with said controller for detecting a position of said roll along a second axis relative to said weld box that is substantially perpendicular to said first axis.
 3. The system of claim 2, further comprising said controller being operable to displace said roll along said second axis relative to said weld box in accordance with a difference between said position of said roll along said second axis and a second position parameter.
 4. The system of claim 3, further comprising an electronic storage unit in data communication with said controller for storing said load parameter and said first and second position parameters.
 5. The system of claim 4, further comprising a processor in data communication with said controller for determining said differences between said position of said roll and said first and second position parameters and said actual load and said load parameter.
 6. A system for monitoring and controlling a tube milling operation, comprising: a weld box; a roll disposed in said weld box for substantially simultaneously compressing and guiding a stock material; a first sensor for detecting an actual load applied to said roll by said stock material; and a controller in data communication with said first sensor and operable to displace said roll along a first axis relative to said weld box in accordance with a difference between said actual load and a load parameter.
 7. A system for monitoring and controlling a tube milling operation, comprising: a weld box; a roll disposed in said weld box for substantially simultaneously compressing and guiding a stock material; a first sensor for detecting an actual load applied to said roll by said stock material; a controller in data communication with said first sensor and operable to displace said roll along a first axis relative to said weld box in accordance with a difference between said actual load and a load parameter; and a second sensor in data communication with said controller for detecting a position of said roll along said first axis.
 8. The system of claim 7, further comprising said controller being operable to displace said roll along said first axis in accordance with a difference between said position of said roll along said first axis and a first position parameter.
 9. The system of claim 8, further comprising a third sensor in data communication with said controller for measuring a position of said roll along a second axis that is substantially perpendicular to said first axis.
 10. The system of claim 9, further comprising said controller being operable to displace said roll along said second axis in accordance with a difference between said position of said roll along said second axis and a second position parameter.
 11. The system of claim 10, further comprising said first sensor including a load cell operably engaged by said roll.
 12. The system of claim 11, further comprising said second and third sensors including optical measurement devices.
 13. The system of claim 12, further comprising an electronic storage unit in data communication with said controller for storing said load parameter and said first and second position parameters.
 14. The system of claim 10, further comprising a processor in data communication with said controller for determining said differences between said position of said roll and said first and second position parameters and said actual load and said load parameter.
 15. A system for monitoring and controlling a tube milling operation, comprising: a weld box; a roll disposed in said weld box for substantially simultaneously compressing and guiding a stock material; a first sensor for detecting a position of said roll along a first axis relative to said weld box; and a controller in data communication with said first sensor and operable to displace said roll along said first axis relative to said weld box in accordance with a difference between said position of said roll along said first axis relative to said weld box and a first position parameter.
 16. A system for monitoring and controlling a tube milling operation, comprising: a weld box; a roll disposed in said weld box for substantially simultaneously compressing and guiding a stock material; a first sensor for detecting a position of said roll along a first axis relative to said weld box; a controller in data communication with said first sensor and operable to displace said roll along said first axis relative to said weld box in accordance with a difference between said position of said roll along said first axis relative to said weld box and a first position parameter; and a second sensor in data communication with said controller for detecting an actual load applied to said roll by said stock material.
 17. The system of claim 16, further comprising said controller being operable to displace said roll along said first axis in accordance with a difference between said actual load and a load parameter.
 18. The system of claim 17, further comprising a third sensor in data communication with said controller for detecting a position of said roll along a second axis that is substantially perpendicular to said first axis.
 19. The system of claim 18, further comprising said controller being operable to displace said roll along said second axis in accordance with a difference between said position of said roll along said second axis and a second position parameter.
 20. The system of claim 16, further comprising said second sensor including a load cell operably engaged by said roll.
 21. The system of claim 18, further comprising said first and third sensors each including an optical measurement device.
 22. The system of claim 19, further comprising an electronic storage unit in data communication with said controller for storing said load parameter and said first and second position parameters.
 23. A method for monitoring and controlling a tube milling operation using a weld box and a roll disposed in the weld box for substantially simultaneously compressing and guiding a stock material, the method comprising: detecting at least one of an actual load applied to the roll by the stock material and a position of the roll along a first axis relative to the weld box; and displacing the roll along said first axis relative to the weld box in accordance with a difference between at least one of said actual load and a predetermined load parameter and said position of the roll along said first axis and a first predetermined position parameter.
 24. A method for monitoring and controlling a tube milling operation using a weld box and a roll disposed in the weld box for substantially simultaneously compressing and guiding a stock material, the method comprising: detecting at least one of an actual load applied to the roll by the stock material and a position of the roll along a first axis relative to the weld box; displacing the roll along said first axis relative to the weld box in accordance with a difference between at least one of said actual load and a predetermined load parameter and said position of the roll along said first axis and a first predetermined position parameter; and retrieving said predetermined load parameter and said first predetermined position parameter from an electronic storage unit prior to displacing the roll.
 25. The method of claim 23, further comprising detecting at least one of said actual load applied to the roll and said position of the roll along said first axis including at least one sensor transmitting a signal to a controller.
 26. The method of claim 23, further comprising: detecting a position of the roll along a second axis relative to the weld box that is substantially perpendicular to said first axis; and displacing the roll along said second axis relative to said weld box in accordance with a difference between said position of the roll along said second axis and a second predetermined position parameter.
 27. A method of automatically monitoring and controlling a tube milling operation, comprising: receiving a load signal from a first sensor, said load signal corresponding to a load applied to a roll in a weld box by a stock material; comparing said load signal to a load parameter; and displacing said roll along a first axis relative to said weld box in accordance with a difference between said load signal and said load parameter.
 28. A method of automatically monitoring and controlling a tube milling operation, comprising: receiving a load signal from a first sensor, said load signal corresponding to a load applied to a roll in a weld box by a stock material; comparing said load signal to a load parameter; displacing said roll along a first axis relative to said weld box in accordance with a difference between said load signal and said load parameter; receiving a first position signal from a second sensor, said first position signal corresponding to a position of said roll along said first axis; comparing said first position signal to a first position parameter; and displacing said roll along said first axis in accordance with a difference between said first position signal and said first position parameter.
 29. The method of claim 28, further comprising: receiving a second position signal from a third sensor, said second position signal corresponding to a position of said roll along a second axis that is substantially perpendicular to said first axis; comparing said second position signal to a second position parameter; and displacing said roll along said second axis in accordance with a difference between said second position signal and said second position parameter.
 30. The method of claim 27, further comprising retrieving said load value from an electronic storage unit prior to comparing said load signal to said load value.
 31. The method of claim 28, further comprising retrieving said first position parameter from an electronic storage unit prior to comparing said first position signal to said first position parameter.
 32. The method of claim 29, further comprising retrieving said second position parameter from an electronic storage unit prior to comparing said second position signal to said second position parameter.
 33. The method of claim 29, further comprising displacing said roll along said first and second axes including automatically actuating a motor operably attached to said roll.
 34. A method of automatically monitoring and controlling a tube milling operation, comprising: retrieving a first position parameter from an electronic storage unit; receiving a first position signal from a first sensor, said position signal corresponding to a position of a roll along a first axis in a weld box; comparing said first position signal to said first position parameter; and displacing said roll along said first axis in accordance with a difference between said first position signal and said first position parameter.
 35. A method of automatically monitoring and controlling a tube milling operation, comprising: retrieving a first position parameter from an electronic storage unit; receiving a first position signal from a first sensor, said position signal corresponding to a position of a roll along a first axis in a weld box; comparing said first position signal to said first position parameter; displacing said roll along said first axis in accordance with a difference between said first position signal and said first position parameter; receiving a load signal from a second sensor, said load signal corresponding to a load applied to the roll by a stock material; comparing said load signal to a load parameter; and displacing said roll along said first axis in accordance with a difference between said load signal and said load parameter.
 36. The method of claim 35, further comprising: receiving a second position signal from a third sensor, said second position signal corresponding to a position of said roll along a second axis that is substantially perpendicular to said first axis; comparing said second position signal to a second position parameter; and displacing said roll along said second axis in accordance with a difference between said second position signal and said second position parameter.
 37. The method of claim 36, further comprising retrieving said first position parameter from an electronic storage unit prior to comparing said first position signal with said first position parameter.
 38. The method of claim 37, further comprising retrieving said load parameter from said electronic storage unit prior to comparing said load signal to said load parameter.
 39. The method of claim 38, further comprising retrieving said second position parameter from said electronic storage unit prior to comparing said second position signal to said second position parameter.
 40. The method of claim 36, further comprising displacing said roll along said first and second axes including automatically actuating a motor operably attached to said roll.
 41. A weld box for use during a tube milling operation, comprising: a sidewall; and a roll rotatably supported in the weld box for substantially simultaneously compressing and guiding a stock material, at least one of said sidewall and said roll being adapted to contain a coolant flow for removing heat from inside the weld box.
 42. A weld box for use during a tube milling operation, comprising: a sidewall; and a roll rotatably supported in the weld box for substantially simultaneously compressing and guiding a stock material, at least one of said sidewall and said roll being adapted to contain a coolant flow for removing heat from inside the weld box and said sidewall including a dual walled side wall defining a flow path for said coolant flow.
 43. The weld box of claim 42, further comprising a hollow shaft rotatably supporting said roll and adapted to contain a coolant flow for removing heat from said roll. 